 The next year, he helped Chris Warren rank first in the AFC with 1,545 rushing yards.Needing help at center after Mark Stepnoski left to the Houston Oilers, the Dallas Cowboys signed Donaldson as an unrestricted free agent on March 20, 1995.That season, he was the NFL's oldest starting center until suffering a broken right ankle and being placed on the injured reserve list, snapping a string of 60 consecutive starts.